1. Field of the Invention
The present invention relates to an injection mechanism of an injection molding machine and particularly relates to an injection mechanism of an injection molding machine using a linear motor as a driving source of the injection mechanism.
2. Description of the Prior Art
An injection mechanism for driving an injection screw of an injection molding machine in axial direction using a motor is already well known. A mechanism for driving this injection screw in the axial direction using a linear motor is also well known by, for example, Japanese Patent Application Laid-Open Nos. 11-58468 and 63-1516 and the like.
In case of an injection mechanism using a conventional linear motor, the linear motor is incorporated integrally into the injection mechanism. Due to this, it is disadvantageously difficult to replace or adjust the linear motor. The linear motor is constituted such that a very small gap is formed between a linear motor movable section (or a needle) making a linearly movement and a linear motor fixed section (or a stator) to thereby allow the movable section to move relatively to the fixed section. The magnitude of this gap influences motor performance. If the linear motor gets out of order and it is necessary to replace it with another linear motor, the replacement operation is difficult to carry out because of the fact that the linear motor is incorporated into the injection mechanism. Further, the adjustment or the like of the gap between the fixed section and the movable section stated above is disadvantageously difficult to make.
It is an object of the present invention to make it possible to reduce dangerous operation using the magnetic force of a linear motor when the linear motor is replaced or repaired and also to easily adjust the gap between the magnet of the linear motor and a coil in the injection mechanism of an injection molding machine using the linear motor as a driving source for longitudinally driving an injection screw shaft.
According to the present invention, an injection mechanism using a linear motor is constituted so that the fixed section of the linear motor extending in an axial direction and facing the movable section of the linear motor linked to the screw shaft and extending in the axial direction is arranged and that a plurality of pairs constituted of an outer frame into which the fixed section is fixedly attached are combined to surround the screw shaft.
In particular, the linear motor movable section is constituted of a polygonal prism having a plurality of pairs of planes parallel to each other. The movable section is linked to an injection screw. Further, the electrical elements of the linear motor are arranged on these pairs of two parallel planes, respectively. On the other hand, the linear motor fixed section is fixedly attached to the outer frame so that the electrical elements of the fixed section face the electrical elements of the linear motor movable section, respectively.
Moreover, the linear motor fixed section has a structure of being detachably attached to the outer frame so that the electrical elements of the fixed section face the electrical elements of the linear motor movable section, respectively. Alternatively, a hole section is provided in the outer frame, a lid closing the hole section is used as the linear motor fixed section and the electrical elements of the linear motor fixed section are fixedly attached to the inside of the lid.